"Antonio Vernucci" wrote in message
...
The Bird actually measures a combination of capacitive coupled voltage
and
inductively coupled current. There is a app note on the Bird website.
Find: "Straight Talk About Directivity".


Thanks for pinpointing that nice document.

However the document dwells on the directivity of the meter, and I could
not
find there any mention of the impedance tolerance issue I had raised.


73

Tony I0JX

The Voltage indication is non directive while the current is directive.
Voltage varies because of impedance and the reactivity causes phase
differences resulting in complex voltages. You should see variations in
both forward and reflected indications.

Functionally, the Bird is best used to minimize whatever reverse indication
without worrying over the accuracy of the derived measurement.